1. Field of the Invention
This invention relates generally to security systems and anti-theft devices. More specifically, it relates to a self-shunting security device for detecting the absence or presence of a removable auxiliary alarm assembly for use in retail stores, offices, and other establishments to prevent theft of items such as electronic devices.
2. Description of the Related Art
In order to deter and prevent the theft of various items from retail stores, offices and other establishments, various security devices and systems employing sensors and alarms have been developed. The current systems generally fall into two categories, closed loop systems and open loop systems.
Closed loop systems typically include an alarm box, a splitter box having a number of ports, sensors and a power supply. These systems are referred to as closed loop systems because a circuit loop is formed when the sensors are properly attached to the articles at one end and to the ports of the splitter box by way of a plug at the other end. In particular, the sensor is in an opened state when it is not attached to an article to be protected. Attachment to the article causes a sensor switch to close, thereby creating a closed circuit with the sensors operatively connected to the alarm box. Once the sensors are connected, the system may be “armed.” As long as the sensors remain attached to the article and operatively connected to the alarm box, the electrical circuit will remain closed and the security system will remain in the armed state. The removal or, in some cases, attempted removal of the sensor from the article acts to open the switch and break the circuit, thereby sounding an alarm.
One of the problems with conventional closed loop systems is that they require shunt plugs to be inserted into unused ports in the splitter box that are not connected to articles in order to complete the circuit and allow the system to be armed. Use of shunt plugs complicates use of the security system because it requires an extra step and the shunt plugs are easily misplaced. Furthermore, as the system will not arm if the plugs of sensors connected to articles or shunt plugs are not occupying all of the ports, there is a risk that lazy or careless employees or personnel may turn off the security device or system (e.g., if one or more of the shunt plugs are lost or misplaced, whereby the system will not arm with the empty port), thereby allowing for possible theft of the articles. The circuit in an open loop system is normally closed when the plugs are inserted into the connections and the sensors are attached to an article, and open upon removal of the sensor from the article. In particular, the sensor switch is typically in an open position when unattached to the article. Attaching the sensor to an article acts to close the switch, thereby allowing current to flow in the circuit. Removal of or tampering with the article's sensor acts to open the sensor switch and actuate the alarm. Any ports that do not have a plug properly inserted therein or that do not have sensors that are attached to articles are considered by open loop systems to be open and therefore not protected by the system.
As an open loop system allows the system to arm even if the ports do not contain either a shunt or a sensor that is attached to an article, one problem with these systems is that it is possible for unscrupulous individuals to manipulate or trick the system in such a way as to permit the articles to be stolen. In particular, an open loop system typically may be circumvented by partially removing the sensor from the article, thereby setting off the alarm if the system is armed. If the personnel monitoring the articles, after turning off the system to quiet the alarm or before turning the system on, does not check to make sure that all of the sensors are properly attached to the articles, when the personnel turns the system back on, the circuit associated with the partially removed plug assembly or improperly attached sensor is therefore open and not protected by the system. Accordingly, the individual can then later come back and remove the article without setting off the alarm. The self-shunting feature of applicant's invention would prevent such 2-step theft. Therefore, there is a need to produce a security device capable of monitoring a variety of different articles that is retailer-friendly, encourages employees to use the system properly, and addresses the problems with the prior systems and devices, while being economical and easy to manufacture.